###############
sub sort_deltas {
###############
 
    my @deltas = @{ shift() };
 
    my $delta;
    my %delta_tmp;
 
    for $delta (@deltas) {
        my $hm = substr($delta,1);
        my @tmp = split /h/, $hm;
        my $h = $tmp[0];
        @tmp = split /m/, $tmp[1];
        my $m = $tmp[0];
        my $minutes = $h * 60. + $m;
 
        my $signum = substr($delta,0,1);
        if ($signum eq '-') {
            $minutes = - $minutes;
        }
        $delta_tmp{$minutes} = $delta;
    }
 
    my $tmp;
    my @tmp_abs;
    my @back;
    push @tmp_abs, sort numerically keys %delta_tmp;
 
    for $tmp (@tmp_abs) {
        push @back, $delta_tmp{$tmp};
    }
 
    return reverse @back;
 
}